1. Field of the Invention
The present invention relates to the tertiary recovery of subterranean hydrocarbons using a solvent, more particularly, to a method and apparatus for the generation of a solvent by the recovery of ethers and other light ends from a liquid mixture of organic compounds recovered from a subterranean deposit.
2. Background Art
There has been increasing interest in maximizing the recovery of crude oil and other subterranean organic materials. This has resulted in a great number of developments of recovery methods using various solvents for recovering crude oil from subterranean reservoirs and for liquefaction of solids such as coal, lignite and shale. There are many reservoirs or subterranean deposits which can yield useful substances but the recovery of which is limited by the cost of the recovery method. As a result, there is an ever present need to reduce the cost of hydrocarbon recovery methods while at the same time providing a method which will not have a detrimental effect on the field or reservoir in which the substances to be recovered are located.
Although a number of solvent recovery techniques and systems for recovering crude oil from underground deposits are known, the recovery and generation of fresh solvents has been a longstanding problem. Some types of solvents for recovering crude oil and the like are difficult to extract from the mixture of solvent and crude and require an input of energy for extraction which, together with the cost of reinjection and driving of the solvents, makes some fields uneconomical for further production even at rapidly escalating prices of oil.
In addition, known processes for liquefaction and extraction of coal using a hydrogenating agent which includes a solvent also require somewhat complex and energy-consuming solvent recovery processes.